Magnetically actuated devices may be designed for a variety of purposes such as, e.g., electrical switching, position sensing, synchronization, flow measurement, and stirring. Particularly important among such devices are so-called reed switches as described, e.g., in the book by L. R. Moskowitz, Permanent Magnet Design and Application Handbook, Cahners Books, 1976, pp. 211-220, in U.S. Pat. No. 3,624,568, issued Nov. 30, 1971 to K. M. Olsen et al., and in the paper by M. R. Pinnel, "Magnetic Materials for Dry Reed Contacts", IEEE Trans. Mag., Vol. MAG-12, No. 6, November 1976, pp. 789-794. Reed switches comprise flexible metallic reeds which are made of a material having semihard magnetic properties as characterized by an essentially square B-H hysteresis loop and high remanent induction B.sub.r ; during operation reeds bend elastically so as to make or break electrical contact in response to changes in a magnetic field.
Among established alloys having semihard magnetic properties are Co-Fe-V alloys known as Vicalloy and Remendur, Co-Fe-Nb alloys known as Nibcolloy, and Co-Fe-Ni-Al-Ti alloys known as Vacozet. These alloys possess adequate magnetic properties; however, they contain substantial amounts of cobalt whose rising cost in world markets causes concern. Moreover, high cobalt alloys tend to be brittle, i.e., to lack sufficient cold formability for shaping, e.g., by cold drawing, rolling, bending, or flattening.
Relevant with respect to the invention are the book by M. Hansen, Constitution of Binary Alloys, 2nd edition, McGraw-Hill, 1958, pp. 677-684; the book by R. M. Bozorth, Ferromagnetism, Van Nostrand, 1951, pp. 102-115 and pp. 180-182; the paper by G. M. Fedash, "Study of Coercivity of Cold-Worked and Annealed Iron Alloys", The Physics of Metals and Metallography, Vol. 4, No. 2, 1957, pp. 50-55; and the paper by S. Jin et al., "The Effect of Grain Size and Retained Austenite on the Ductile-Brittle Transition of a Titanium-Gettered Iron Alloy", Metallurgical Transactions A, Vol. 6A, September 1975, pp. 1721-1726. These references discuss phase transformations, mechanical properties, and coercivity of iron-rich Fe-Ni alloys. Semihard magnetic properties of Fe-Ni and Fe-Mn alloys are disclosed by V. I. Zeldovich et al., "Effect of Heat Treatment on the Magnetic Properties of Certain Alloys of the Systems Fe-Mn and Fe-Ni", Fiz. Metal. Metalloved., Vol. 20, No. 3, pp. 406-411, 1965; and in Japanese patent No. 48-17124, issued May 26, 1973 to T. Takahashi et al.